1. Technical Field
The present invention generally relates to wireless communication systems, and in particular to methods and systems for providing group call functionality within a wireless communication system.
2. Description of the Related Art
Use of wireless networks to provide group calling services is known in the art. Group calling services typically allow member devices (e.g., portable or mobile radios) located within range of the communication system's fixed network elements (FNE) to communicate with each other via a talk group. Some group calling services/systems were designed around frequency division multiple access (FDMA) technology, and the member devices are traditionally FDMA-enabled radios communication using FDMA communication protocols. An example of such a system is the Astro system.
The Astro system supports/dispatches talk groups. The Astro system is typically utilized by public and/or emergency services, such as fire service, hospitals, police, and similar groups to enable simultaneous broadcast/exchange of communication to multiple member devices within the particular talk group. The typical Astro system operates via FDMA protocol, and each radio that joins the talk group is connected via an FDMA channel, if one is available. When the FDMA resources are not available, i.e., there is no available communication frequency on which to connect the new radio, the radio is not able to connect to the talk group.
Conventional Astro systems and radios developed for use therein are typically FDMA-based. Recently, newer types of radios have been developed with time division multiple access (TDMA) capabilities, and these newer radios are being utilized within the conventional FDMA-based Astro systems. When a TDMA radio is added to a talk group via an FDMA site, the access via the FDMA site forces the entire talk group to communicate using FDMA protocol. Thus, with the use of FDMA sites controlling the talk group communications, several limitations are seen with talk group operations, even when the radios themselves are TDMA-capable devices.
FDMA protocol has the limitation of having limited frequency resources to allocate, when compared to other communication protocols (e.g., TDMA, CDMA, etc.). When a TDMA-capable radio affiliates to an FDMA site, the TDMA capable radio is affiliated using FDMA protocol. If the TDMA-capable radio affiliates to a talk group via the FDMA site, and the talk group is operating via the TDMA protocol and only has TDMA-capable radios affiliated therewith, the operational mode of the talk group will be forced to FDMA mode because of the connection of the new radio via the FDMA site. This changing of the talk group's operational mode to an FDMA mode requires all affiliated members of the talk group (i.e., all of the TDMA-capable radios) to fall back to FDMA operation mode, which is less efficient and more resource-intensive.